Adjustable support tools have become quite common for home and industrial use. One example of such adjustable tool is disclosed by Huang in U.S. Pat. No. 6,247,882 (hereinafter “Huang”), issued on Jun. 19, 2001, entitled “CARGO BRACING DEVICE,” and another example of an adjustable tool is disclosed by Shiau in U.S. Pat. No. 5,988,963 (hereinafter “Shiau”), issued on Nov. 23, 1999, entitled “CARGO POSITIONING FRAME.” Both prior patents are incorporated by reference as if fully set forth herein.
The Huang patent discloses a bracing device including a rod slidably received in a tube and having a number of depressions. A lever (35) is pivotally secured to the tube and has a pawl (80) for engaging with the depressions (12) of the rod. A blade (40) is pivotally secured to the tube and has a bulge (43) for engaging with the depressions of the rod. A shaft (50) is slidably received in the tube and engaged with the blade for biasing the bulge to engage with the depressions of the rod. The shaft is selectively engaged with the lever for selectively forcing the pawl to secure the rod to the tube.
The Shiau patent discloses a tube of a cargo positioning frame made of a plate. The plate has a plurality of positioning holes and a plurality of upper chamfer angled holes. Each of the upper chamfer angled holds communicates with the respective positioning holes in order to position a pawl stably.
Such conventional adjustable tools still have their drawbacks. First, in the Huang patent, the shaft (50) often fails to provide a clear indication as to whether the lever is engaged or disengaged, thus creating confusion to the users. Also, as in both Huang and Shiau patents, a secondary, or fine, adjustment other than the positioning of the depressions (12) is often needed by the user, since the positions of the depressions are fixed and cannot accommodate too much variation. Last but not least, the pawl tends to scratch the paint off the surface of the rod when the rod is moved, thus causing the rod to be oxidized over time.